Investigation of a new UAV configuration with non-elliptic lift distribution

Abstract

The development of an alternative wing-body-tail configuration is investigated using the AREND UAV as a baseline. The proposed configuration, inspired from bird wings, assumes that all stability requirements are achieved through the main wing and there is no need for an empennage. The potential here is not only a reduction in structural weight, but also a reduction in drag that leads to an increase in fuel efficiency. This study uses the AREND wing with elliptic loading and compares its characteristics to the new wing design that has a non-elliptic lift distribution (NELD) using the method developed by Prandtl in 1933. Both the AREND and NELD wings are analysed using computational fluid dynamics to investigate the aerodynamics and flight mechanics bene ts of the NELD configuration. The AREND and NELD comparison shows that the NELD configuration increases the aerodynamic efficiency by 9:87% due to the higher lift to drag ratio and the removal of the empennage. Further benefits include weight reduction and a wider CG range. A smaller wake region was also found due to the wing being fully blended with the fuselage. Upwash was seen to occur at 2y=b = 0.85 indicating the presence of induced thrust as predicted and shown by Prandtl and the Horten Brothers. The change in lift distribution over the wing due to sideslip also shows that the NELD configuration exhibits proverse yaw and therefore, can indeed perform a coordinated turn.